Casne is writing a series of blogs about digital twins and their applications in the industries we serve. In this blog, we'll present a bit more about SCADA and BMS, as well as their histories. Stay tuned for the third one, in which we will write about how digital twins differ from and relate to SCADA systems and building management systems.
SCADA systems’ origin can be traced back to the 1930s when telephone companies began using a new technology to switch circuits. Electric utilities quickly adopted the same technology but kept people involved in checking its actions. In the 1950s, companies began using telephony systems to relay information without direct human involvement. The following decade, as transistors and microprocessors began to enter the mainstream, the first true SCADA systems came into existence, gaining their name around 1965. From there, the systems evolved along with the hardware and software that powered them. Initially, they only traded information between a mainframe computer and remote terminal units (RTUs). Then, they became distributed systems that featured stations that communicated among themselves as well as with the mainframe on local area networks. Finally, they evolved into networked systems in which the communication is based on open protocols that allow for wide area networks (WANs) and the use of what are now common peripheral devices, such as printers and monitors.
An article from a 2016 issue of “Bulletin of the Transilvania University of Braşov” lists the components of SCADA systems as:
- The RTU, which collects data from sensors, digitizes it and sends it to the supervisory system, as well as receives commands from the supervisory system;
- The programmable logic controller (PLC), which is similar to the RTU, but can locally control processes and execute logic operations;
- The telemetry system, which provides communication functions;
- The data acquisition server, which is based on client-server architecture and industrial protocols and allow clients to access data from RTUs and PLCs;
- The human machine interface (HMI), which presents the data gathered from RTUs and PLCs to the people monitoring and/or running the system;
- The historian service, which accumulates all the information gathered from the system and stores it in databases;
- And the supervisory control, which is the computer that can control everything connected to the system.
BMS are much simpler than SCADA systems and a little younger, too, with most people saying they first emerged in recognizable form a little more than 50 years ago. Their roots, however, go back much farther, with Automation.com tracing them back to 17th century Dutch inventor Cornelius Drebbel, who developed an incubator thermostat to help warm chicken eggs and get them to hatch. A more directly relevant milestone occurred in 1883 when Milwaukee school teacher Warren Johnson, who would go on to found Johnson Controls, invented the building thermostat.
The first BMS were designed just to manage HVAC systems, which they did through pneumatic controls that transmitted signals to equipment by sending compressed air through tubes. Pneumatically controlled systems and hybrid systems that use compressed air and electronics, are still being used to control HVAC systems today. Of course, there are also BMS that use computers to control buildings’ mechanical and electrical equipment, and while the evolution of their HVAC components involved moving from pneumatic to electronic controls, other subsystems, such as lighting, were always electronically controlled. BMS technology has evolved to the point that it runs or monitors multiple systems, including HVAC, lighting, elevator and escalator, security, fire safety and building access. A major step in that evolution was the 1995 introduction of BACnet, a communications protocol whose name is an acronym for building automation control network.
In the last decade, internet of things (IoT) technology has made integration of building subsystems even easier, allowed BMS to be managed remotely from such devices as laptop computers and smartphones, and given rise to building information management, which enables BMS technology to be incorporated into a building’s design.
IoT technology also makes smart building possible. In it, sensors, software, and connectivity are used to monitor activity, spot usage patterns and generate insights about how to manage the building to respond to them, or, in some cases, respond to them automatically. An example of an automatic response would be an adjustment to a building’s outside air intake according to the amount of carbon dioxide in the building.
Just as IoT technology is becoming part of BMS to enable smart buildings, it is being deployed on top of SCADA systems to enable smart factories and smart grids. IoT technology, or as it’s called in industrial applications, IIoT (industrial internet of things) technology also helps make possible the digital twins that are the subject of our blog series to which this is a companion piece.